Make blinky service-ready

New features include:
 - General robustness
 - Configurable config path
 - MQTT retry

blinky.py

@@ -5,7 +5,9 @@ import board
 import neopixel
 import json
 import os
+import sys
 import time
+from pathlib import Path
 
 import pyinotify, threading
 import paho.mqtt.subscribe as subscribe
@@ -16,22 +18,34 @@ from pattern import Pattern
 lock_reload = threading.Lock()
 cond_reload = threading.Condition(lock_reload)
 reload = False
-config = None
+ignore_file = False
+config = {}
+new_config = None
 
 
 # Monitor config from file
 
-config_file = "blinky.json"
+if len(sys.argv) > 1:
+    config_file = sys.argv[1]
+else:
+    config_file = "blinky.json"
+
+if not Path(config_file).is_file():
+    print("WARNING: Config file does not exist:", config_file)
 
 def file_thread(file):
     class EventHandler(pyinotify.ProcessEvent):
         def process_IN_CLOSE_WRITE(self, event):
-            global reload, config
+            global reload, new_config, ignore_file
             with lock_reload:
-                print("Triggering file reload")
-                config = None
-                reload = True
-                cond_reload.notify_all()
+                if ignore_file:
+                    print("Ignoring file change")
+                    ignore_file = False
+                else:
+                    print("Triggering file reload")
+                    new_config = None
+                    reload = True
+                    cond_reload.notify_all()
 
     wm = pyinotify.WatchManager()
     notifier = pyinotify.Notifier(wm, EventHandler())
@@ -52,17 +66,37 @@ class mqtt:
 
 def mqtt_thread():
     def on_message(client, userdata, message):
-        global reload, config
+        global reload, new_config
         with lock_reload:
             print("Triggering MQTT reload")
             try:
-                config = json.loads(message.payload)
+                new_config = json.loads(message.payload)
                 reload = True
                 cond_reload.notify_all()
             except:
                 print("Invalid MQTT config")
 
-    subscribe.callback(on_message, mqtt.topic, hostname=mqtt.hostname, auth=mqtt.auth, port=8883, tls=mqtt.tls)
+    global reload, new_config
+    while True:
+        print(f"Subscribing to MQTT topic {mqtt.topic}")
+        try:
+            message = subscribe.simple(mqtt.topic, hostname=mqtt.hostname, auth=mqtt.auth, port=8883, tls=mqtt.tls)
+        except Exception as e:
+            print("MQTT subscription error:", e)
+            message = None
+        if not message:
+            print("Subscription failed - retrying")
+            time.sleep(1)
+        else:
+            with lock_reload:
+                print("Triggering MQTT reload")
+                try:
+                    new_config = json.loads(message.payload)
+                    reload = True
+                    cond_reload.notify_all()
+                except:
+                    print("Invalid MQTT config")
+
 
 threading.Thread(target=mqtt_thread).start()
 
@@ -81,27 +115,37 @@ with lock_reload:
         reload = False
 
         try:
-            config = config or json.load(open(config_file))
-
-            new_length = config['length']
-
-            if length != new_length:
-                print("New string config")
-                length = new_length
-                pixels = neopixel.NeoPixel(board.D18, length, pixel_order=neopixel.RGB, auto_write=False)
-                #pixels = TermLEDs(length)
-
-            patterns = [(pattern['length'], Pattern.from_dict(pattern)) for pattern in config['patterns']]
+            # If it wasn't delivered, load from file
+            new_config = new_config or json.load(open(config_file, 'r'))
+
+            if 'length' in new_config:
+                new_length = new_config['length']
+                if length != new_length:
+                    length = new_length
+                    config['length'] = length
+                    pixels = neopixel.NeoPixel(board.D18, length, pixel_order=neopixel.RGB, auto_write=False)
+                    #pixels = TermLEDs(length)
+                    print("String configured")
+
+            patterns = [(pattern.get('length', length), Pattern.from_dict(pattern)) for pattern in new_config['patterns']]
+            config['patterns'] = new_config['patterns']
+            print("Pattern configured")
 
         except Exception as e:
             print("Failed to load config:", e)
 
-        if not pixels or not patterns:
+        finally:
+            print("Saving config")
+            ignore_file = True
+            json.dump(config, open(config_file, 'w'))
+
+        if not length or not pixels or not patterns:
             print("Waiting for valid config")
             while not reload:
                 cond_reload.wait()
         else:
-            target = time.time()
+            print("Starting animation")
+            last = target = time.time()
             while not reload:
                 lock_reload.release()
 
@@ -112,7 +156,8 @@ with lock_reload:
                 # Go ahead and sleep, maintaining maximum framerate
                 target += (1 / framerate)
                 now = time.time()
-                if target > now:
-                    time.sleep(target - now)
+                sleeptime = target - now
+                if sleeptime > 0:
+                    time.sleep(sleeptime)
 
                 lock_reload.acquire()